Pieter-Jan Pauwels (Open Knowledge Belgium) has set up a poll to allow crowd sourcing for the most favorable date for Open Data Day (ODD) 2017. I would encourage all interested to make their preference known. Extract from his email (with the link) is below.

I used pollandmatch.com. It does ask a name and email, but no worries, we will not steal your ID or sell your data to any 3rd party.